2003 Suburban 5.3z occasional hard start.
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CF Beginner
Joined: Jan 2020
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From: Wisconsin
2003 Suburban 5.3z occasional hard start.
Hey guys,
new here and at my wits end with an occasional hard start. It always starts right up cold and usually restarts fine within a few minutes of shutting down. When it is at operating temperature and it sits for 15min to an hour it will randomly start hard. It will crank and try to start, kick the starter back and try again. Usually takes two or three tries. Once running it is perfect.
I originally assumed it was the fuel pump check valve or regulator. So, against my better judgment I replaced both before ever putting my pressure gauge on it. Needless to say I still have an issue $300 later. I have since connected my pressure gauge to watch what is happening. Currently my fuel pressure is at spec for the 5.3Z. When it acts up the engine is warm, It will loose fuel pressure slowly after holding steady for 15 minutes and slowly drop to zero over the next hour. If I try to restart too soon it has trouble. let it cool off and it starts up fine. I suspect an injector leak but it happens so randomly I doubt I will find it by pulling the rail and pressurizing it.
Looking for some ideas here.
new here and at my wits end with an occasional hard start. It always starts right up cold and usually restarts fine within a few minutes of shutting down. When it is at operating temperature and it sits for 15min to an hour it will randomly start hard. It will crank and try to start, kick the starter back and try again. Usually takes two or three tries. Once running it is perfect.
I originally assumed it was the fuel pump check valve or regulator. So, against my better judgment I replaced both before ever putting my pressure gauge on it. Needless to say I still have an issue $300 later. I have since connected my pressure gauge to watch what is happening. Currently my fuel pressure is at spec for the 5.3Z. When it acts up the engine is warm, It will loose fuel pressure slowly after holding steady for 15 minutes and slowly drop to zero over the next hour. If I try to restart too soon it has trouble. let it cool off and it starts up fine. I suspect an injector leak but it happens so randomly I doubt I will find it by pulling the rail and pressurizing it.
Looking for some ideas here.
Last edited by George B; Jan 8, 2020 at 9:45 PM.
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Thread Starter
CF Beginner
Joined: Jan 2020
Posts: 10
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From: Wisconsin
sounds a lot like the ice cream story
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Joined: Sep 2019
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Hey guys,
new here and at my wits end with an occasional hard start. It always starts right up cold and usually restarts fine within a few minutes of shutting down. When it is at operating temperature and it sits for 15min to an hour it will randomly start hard. It will crank and try to start, kick the starter back and try again. Usually takes two or three tries. Once running it is perfect.
I originally assumed it was the fuel pump check valve or regulator. So, against my better judgment I replaced both before ever putting my pressure gauge on it. Needless to say I still have an issue $300 later. I have since connected my pressure gauge to watch what is happening. Currently my fuel pressure is at spec for the 5.3Z. When it acts up the engine is warm, It will loose fuel pressure slowly after holding steady for 15 minutes and slowly drop to zero over the next hour. Ryan Harvey of Autofthings reivews best multimeter for automotive use. If you want to get one, visit this site and review his post. If I try to restart too soon it has trouble. let it cool off and it starts up fine. I suspect an injector leak but it happens so randomly I doubt I will find it by pulling the rail and pressurizing it.
Looking for some ideas here.
new here and at my wits end with an occasional hard start. It always starts right up cold and usually restarts fine within a few minutes of shutting down. When it is at operating temperature and it sits for 15min to an hour it will randomly start hard. It will crank and try to start, kick the starter back and try again. Usually takes two or three tries. Once running it is perfect.
I originally assumed it was the fuel pump check valve or regulator. So, against my better judgment I replaced both before ever putting my pressure gauge on it. Needless to say I still have an issue $300 later. I have since connected my pressure gauge to watch what is happening. Currently my fuel pressure is at spec for the 5.3Z. When it acts up the engine is warm, It will loose fuel pressure slowly after holding steady for 15 minutes and slowly drop to zero over the next hour. Ryan Harvey of Autofthings reivews best multimeter for automotive use. If you want to get one, visit this site and review his post. If I try to restart too soon it has trouble. let it cool off and it starts up fine. I suspect an injector leak but it happens so randomly I doubt I will find it by pulling the rail and pressurizing it.
Looking for some ideas here.
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Joined: Feb 2019
Posts: 1,467
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From: Maryland
to add to what ricardo said. next time it acts up the first time just cycle the key a couple times just to "acc" and not actually engage the starter. after two-three times fuel pressure should be built back up. if it starts then you know its the fuel pump
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CF Beginner
Joined: Jan 2020
Posts: 10
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From: Wisconsin
Here is the sequence of events:
- Turn key to start
- Engine turns over (count of one)
- Engine fires for count of one and dies kicking starter back.
- Sometimes starter continues to try cranking and grinds the flywheel.
- Repeat until started.
Parts to date:
Fuel pump
Fuel pressure regulator.
ECT sensor
Service attempts and checks:
Clean MAF
IAT is correct.
Check MAP KOEO 14.5 PSI
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